RE: pfim

> -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Annick Rousseau > Sent: Tuesday, 28 September 2010 4:09 a.m. > To: [email protected] > Subject: [NMusers] pfim > > > > Dear NM-users, > > We developed a PK model using NONMEM for a drug using a 2-cpt model with > time-lagged first order absorption and first order elimination. The > final model includes binomial covariates correlated with clearance, > absorption rate and bioavailability. The model is validated using a VPC. > We split our data set in an index data set to develop a Bayesian > estimator and a separated validation data set to determine its > predictive performance. We are using PFIM3.2.1 in order to determine the > optimal sampling schedule using the popPK parameters as estimated for > the index data set. However, we are having some issues, for which we > need some suggestions. > > - The model has a time-lagged absorption. How can we include this in our > PFIM files? > > - The covariates in our final model are coded proportionally. We use an > exponential random effect model (see below). How can we include our > covariates in this model? Do we need to transform the value from the > nonmem output file? > Nonmem: CL=THETA(1)*THETA(2)**COV > PFIM: > # covariate is additive on log parameters if exponential random effect > model (Trand=2) > #----------------------------------------------------------------------- > beta.covariate<-list(COV=list(c(log(1.93)))) > > - We have a covariate and interpatient variability on bioavailability. > How can we code this in PFIM? > > - Furthermore, we developed a second model using Erlang distribution to > describe the absorption. Does anybody know how to implement this in PFIM? > > Thank you very much in advance for your help. > > Kind regards, > Annick Rousseau and Brenda de Winter